THE LANGE 1815 UP and DOWN:
THE CALIBER L942.1


BY WALT ODETS












































The Lange & Sohne 1815 Up and Down is perhaps the quintessential Lange watch. Utterly traditional in appearance, it encases the caliber L942.1, a caliber L941.1 with the addition of a true differential power reserve mechanism. The addition of the power reserve gearing increases the thickness of the 11 ligne (25.6 millimeter) movement by 0.38 millimeter, for a total thickness of 3.58 millimeters. The 942.1 uses 27 jewels, 21 in the timing train (jeweled to the barrel, with two cap jewels on the escape wheel) and an additional six in the power reserve mechanism. The caliber provides stop seconds (“hacking”) and, like most Langes, beats at 21,600. The watch case measures 36 millimeters in diameter and 7.96 millimeters thick.


BASIC CONSTRUCTION

Like all hand wound Langes to date, the caliber 942 uses a three-quarter bridge construction. This single plate provides upper pivots for all mechanisms in the watch, save the balance wheel. Thus the movement is constructed of only four structural components: the three-quarter plate, the
main plate, the pallet lever bridge, and the balance cock. All plates and bridges are fabricated of nickel silver, an alloy of copper, nickel, and zinc. They are unplated. While providing a traditional and distinctive color and sheen, the plates are soft and easily scratched.



As illustrated left, the immaculately finished three-quarter bridge is decorated with a striped pattern on the top surface, and six of the eight pivots are set with screwed, gold-chatoned jewels. The escape wheel uses uses a traditional black-polish steel plate for cap jewel retention (1), and the seconds intermediate wheel uses a friction-fit gold chaton (2). All visible finishing is done with a distinctly German aesthetic that could not be mistaken for a Swiss watch. A screwed chaton, as seen from underneath the three-quarter plate is illustrated below right.





























The Three-quarter bridge and stripped
main plate of the movement are shown left.





























The click mechanism (left) is mounted to the underside of the three-quarter plate and uses an unusual design. A single-toothed click with elongated slot (1), it must relieve excessive tension on the mainspring at full wind by sliding on its mounting screw (rather than rotating as with a double tooth design). Properly lubricated, this common, older design should work properly. However, because of the sliding friction on both the screw and the click spring (2), these clicks are prone to sticking. Most Langes carrying a paper tag on the buckle warning the owner to relieve tension on the mainspring by “back-winding” the crown after arriving at full wind. Note the convenient hole in the plate (3) and click (4) for releasing mainspring pressure during service.















TOP PLATE DETAILS

As illustrated right with all components in place on the top late, the three-quarter bridge encompasses the upper pivots of no fewer than eight components. These are (1) the mainspring barrel; (2) power reserve upper differential wheel;
(3) center wheel; (4) third wheel; (5) fourth wheel; (6) escape wheel; (7) seconds intermediate wheel; and (8) seconds wheel. The pallet lever bridge is indicated at (9), the lower balance jewel assembly at (10).
















































Among other beautiful details on the top plate is the exquisitely fabricated stop lever (right). When the crown is pulled into the setting position, the lever pivots and its extremely fine tip (right end) places a slight pressure on the balance wheel.


The pallet lever bridge and pallet lever itself are beautifully finished. The unexpected brass bushing (arrow) in the
main plate carries the pinion of the power reserve indicator wheel. This must be very sparingly lubricated to avoid contamination of the balance spring.

 

 

The setting lever (pull piece) of the Lange is of an unusual design (right). Instead of the setting lever screw (2) engaging the pull piece directly, a spring (1) is used. The pull piece screw tensions the spring which carries a post (3) on the setting lever. This provides some flexibility to the pull piece, likely helping prevent breakage of the stem with a shock to the crown. This photograph also shows the pin on the set lever (4) that operates the stop lever (5) when the crown is pulled into the hand-setting position.

The crown wheel (right, 1) is very elegantly provided with its own cock (2).
















































Because the seconds display on the dial is moved from the six to the four o’clock position, the 1815 Up and Down uses an indirect subsidiary seconds (left). The fourth wheel (1) drives a seconds intermediate wheel (2), which in turn drives the seconds indicator wheel (3). Because an indirect center seconds is out of the power flow (not between mainspring and balance), the display is prone to fluttering. It is common to see a tensioning spring to correct this on indirect center seconds (where the size of the display makes the fluttering more obvious), but Lange uses a tension spring on this caliber too (4). The spring rides in an elegantly machined track on the pinion of the indicator wheel (below left).

While the spring is accessible through the main plate behind the dial, it is unfortunate that Lange did not also provide a hole in the three-quarter bridge to allow adjustment of the spring tension. Inadequate tension provides an unstable seconds display, while excessive tension can reduce the amplitude of the movement significantly.











CONTINUE TO PART 2 OF THE ARTICLE


 
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